Dallas anchors the eastern side of the Dallas–Fort Worth metroplex in North Texas and serves as the seat of Dallas County. Long a crossroads of railroads and later a hub of banking, insurance, and technology, the city grew into one of the nation's major corporate centers. Its business base includes the global headquarters of Texas Instruments, AT&T, Comerica, and Southwest Airlines, while the broader region claims more than twenty Fortune 500 headquarters. That concentration of employers makes Dallas a destination for professionals relocating within Texas and from across the country. The city's geography is flat to gently rolling prairie crossed by the Trinity River, and its development reflects more than a century of growth: a dense downtown and Arts District core ringed by historic streetcar suburbs, mid-century neighborhoods around White Rock Lake, and extensive newer subdivisions spreading across far North Dallas and into surrounding counties. Residents range from young professionals drawn to Uptown and Deep Ellum to families in established East Dallas neighborhoods and suburban-style northern communities. Dallas balances its corporate identity with a substantial cultural footprint. The walkable Arts District clusters the Dallas Museum of Art, the Nasher Sculpture Center, the Crow Museum of Asian Art, and the Perot Museum of Nature and Science around Klyde Warren Park, which functions as an informal town square built over a freeway. The State Fair of Texas, one of the nation's largest, unfolds each year at Fair Park east of downtown, while White Rock Lake and the city's growing trail network provide a green counterweight to the skyline. Public education is anchored by Dallas ISD, with numerous independently governed suburban districts serving surrounding communities and giving families a wide range of school choices.